If (2,0) is the vertex and y-axis the directrix of a parabola find the focus of the parabola. What does y-axis is directrix mean here?
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See the third example in http://www.purplemath.com/modules/parabola3.htm – lab bhattacharjee Apr 30 '16 at 08:38
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But we aren't provided with a value of directrix here. – Bismeet singh Apr 30 '16 at 08:42
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What do you mean by "a value of directrix"? – lab bhattacharjee Apr 30 '16 at 08:45
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Something like y= a constant – Bismeet singh Apr 30 '16 at 08:45
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The parabola is the locus of points that are equidistant from both a given line (the directrix) and a point (the focus).
Normally, you are given the data to give the results in terms of $x$: a directrix $y=\cdots$ for a parabola $y=\cdots$. But in this case, your directrix is $x=0$. Just try to follow the same directives but interchanging $x$ and $y$; you will obtain a parabola of the form $x=\cdots$ instead of $y=\cdots$
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